In copending patent application Ser. No. 149,291, filed May 12, 1980 entitled Repeatered, Multichannel Fiber Optic Communication Network Having Fault Isolation System, by P. Casper et al, and assigned to the assignee of the present application, there is described a communication network for conveying high density, high data rate digital signalling traffic over plural fiber optic channels between geographically separated terminal stations. Distributed along the fiber optic links between the terminal stations are a plurality of repeater sites at which the signals are regenerated as they travel over the fiber optic cables. In addition to the normally active fiber optic channels over which digitized data signals are transmitted in the form of an encoded optical pulse stream, the network described in the above identified application contains auxiliary equipment that serves as a backup in the event of a failure in the normally used links.
In this type of system, as well as other repeatered and multichannel environments, it is often required that the communication links over which the data is transmitted be augmented or served by an auxiliary monitor and control subsystem that performs required housekeeping chores with respect to the transmission channels and regenerator equipment distributed along the communication links. Preferably, this auxiliary equipment should operate independently of the main transmission section of the network so that an interruption or degradation of service over the data-conveying links will not impair the operation of the monitor and control function of the supervisory equipment.